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Electronics => Beginners => Topic started by: jayfehr on March 10, 2016, 04:09:53 pm

Title: Best methods for getting an electric guitar signal into an Arduino or RPi
Post by: jayfehr on March 10, 2016, 04:09:53 pm
Hi, I'm wondering what the best approach is to getting the line-in signal from an electric guitar into a microcomputer or microcontroller for effects processing? The Pi has i2s, as does the Adafruit M0 feather so I'm thinking that is the best way to get the signal in, but what additional hardware will I need? Which i2s chip? Will I need a voltage divider or an op-amp? What are some gotcha's? I'm really just hoping for a starting point.

Thanks in advance.
Title: Re: Best methods for getting an electric guitar signal into an Arduino or RPi
Post by: ade on March 10, 2016, 05:35:47 pm
i2s is digital so you need to build an ADC i2s circuit, for example using TI's PCM1802 chip or similar.  That might be a project on itself.

And unfortunately you'll find that i2s for audio input is not very well supported on PIs, etc. and may require some kernel hacking to get it to work reliably.

So depending on your expectations, you might be better off just buying a $5 USB sound card and use that for input.

E.g.,:

https://www.youtube.com/watch?v=bLcW70tcBX8 (https://www.youtube.com/watch?v=bLcW70tcBX8)
Title: Re: Best methods for getting an electric guitar signal into an Arduino or RPi
Post by: danadak on March 10, 2016, 05:37:03 pm
Is the line in signal a direct output of guitar pickup ? Or is the
line in signal a processed signal from a guitar amp ?

In either case what are signal levels with respect to ground ?

Regards, Dana.
Title: Re: Best methods for getting an electric guitar signal into an Arduino or RPi
Post by: netdudeuk on March 10, 2016, 10:41:23 pm
Seen the latest Ben Heck video with Felix doing a guitar mod ?
Title: Re: Best methods for getting an electric guitar signal into an Arduino or RPi
Post by: kolonelkadat on March 10, 2016, 11:11:13 pm
the peak output voltage of the guitar should be somewhere in the like 200mv-1v range, so if you went with an arduino, you'd probably want to feed the signal into an opamp before running it into the adc. im not sure the 12bit adc on the feather you mentioned will give the greatest sound, but it might make for some decent chiptunes.

the raspberry pi is literally just a crappy computer, you get audio into it the same way you would on any other computer. a sound card.